Bacher Andreas Kvist, Pedersen Ulf R, Schrøder Thomas B, Dyre Jeppe C
Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark.
J Chem Phys. 2020 Mar 7;152(9):094505. doi: 10.1063/1.5144871.
This paper studies numerically the solid phase of a system of particles interacting by the exponentially repulsive pair potential, which is a face-centered cubic (fcc) crystal at low densities and a body-centered cubic (bcc) crystal at higher densities [U. R. Pedersen et al., J. Chem. Phys. 150, 174501 (2019)]. Structure is studied via the pair-distribution function and dynamics via the velocity autocorrelation function and the phonon density of states. These quantities are evaluated along isotherms, isochores, and three isomorphs in both crystal phases. Isomorphs are traced out by integrating the density-temperature relation characterizing configurational adiabats, starting from state points in the middle of the fcc-bcc coexistence region. Good isomorph invariance of structure and dynamics is seen in both crystal phases, which is notable in view of the large density variations studied. This is consistent with the fact that the virial potential-energy correlation coefficient is close to unity in the entire fcc phase and in most of the bcc phase (basically below the re-entrant density). Our findings confirm that the isomorph theory, developed and primarily studied for liquids, applies equally well for solids.
本文对由指数排斥对势相互作用的粒子系统的固相进行了数值研究，该系统在低密度下为面心立方（fcc）晶体，在较高密度下为体心立方（bcc）晶体[U. R. Pedersen等人，《化学物理杂志》150, 174501 (2019)]。通过对分布函数研究结构，通过速度自相关函数和声子态密度研究动力学。这些量沿着等温线、等容线以及两个晶相中的三条同构线进行评估。同构线是通过对表征构型绝热线的密度 - 温度关系进行积分得到的，从fcc - bcc共存区域中间的状态点开始。在两个晶相中都观察到结构和动力学具有良好的同构不变性，鉴于所研究的密度变化较大，这一点值得注意。这与维里势能相关系数在整个fcc相和大部分bcc相（基本上低于再入密度）中接近1的事实是一致的。我们的研究结果证实，最初为液体发展并主要针对液体进行研究的同构理论，同样适用于固体。
